Pet foods are generally manufactured and available in dry, moist and semi-moist formulations.
Dry pet foods, which typically contain less than about 15 percent moisture, are formed primarily from farinaceous materials, and may contain small amounts of proteinaceous material and flavorings to improve palatability, as well as nutrients to insure a proper diet for the animal. While dry pet foods have excellent biological stability and can be packaged in bulk containers that need not be used immediately after opening, such drypet foods also are often relatively low in palatability for the animal and low in perceived attraction to the consumer who purchases the product.
U.S. Pat. No. 3,615,647 (Kassens) discloses the production of expanded, fat-coated animal food having a coherent coating. The fat coating is overlaid with a coherent coating containing dextrinized starch. See for example column 3, lines 30 to 57, of Kassens.
U.S. Pat. No. 4,104,406 (Stringer et al.) discloses porous, expanded animal foods which are coated with a fat/dextrin material emulsion. See for example column 2, lines 48 to 56, of Stringer et al.
U.S. Pat. No. 4,211,797 (Cante et al.) discloses dog foods having a surface coating of a blend of a lipolyzed beef tallow and a digest of beef. The digest of beef can have a pH of 2.8 to 4.2. See for example column 3, line 64, to column 4, line 26, and the coating compositions of Examples I and II of Cante et al.
U.S. Pat. No. 4,229,485 (Brown et al.) discloses a glazed liver coated biscuit or kibble for pets. Critical to successful coating, it is disclosed, is the use of a slurry of comminuted liver, preferably beef liver, in sufficient concentration, at least 50 percent by weight of the slurry, exclusive of moisture to provide a glazed, encapsulating coating when baked. See for example column 3, lines 43 to 58, of Brown et al. The slurry bath can also contain potassium sorbate. See column 7, lines 16 to 67, and the tables in Examples 3 and 7.
U.S. Pat. No. 4,366,175 (Brown et al.) discloses a glazed liver coated biscuit or kibble for pets wherein a coating slurry comprises comminuted liver and can contain potassium sorbate. See for example the paragraph bridging columns 3 and 4, the paragraph bridging columns 5 and 6, and the tables of Examples 1 to 4, 7 and 12 of Brown et al.
U.S. Pat. No. 4,689,235 (Barnes et al.) discloses an encapsulating matrix composition containing maltodextrin. See for example Examples I to IX of Barnes et al.
U.S. Pat. No. 4,913,919 (Cornwell et al.) discloses a high solids, aqueous coating composition for modifying the texture, flavor and/or color of comestible products. The coating composition comprises from 10 to 40 percent by weight of maltodextrin and from 10 to 40 percent by weight of starch granules. See for example column 3, lines 8 to 67, and Examples 1 to 10 and 21 of Cornwell et al.
U.S. Pat. No. 4,904,494 (Spanier) discloses a chewy, semi-plastic, non-extruded, non-porous, microbiologically-stable dog food which includes 12 to 30 percent by weight of gelatin, at least one acidulent, at least one cereal starch-containing textural agent, at least one release agent, at least one taste agent, and at least one sugar. The dog food is in molded form and has a pH of about 3 to 5. Citric acid is the preferred acidulent. The tartness of the acidulent, it is disclosed, helps to balance the sweetness due to the sugars present in the dog snacks. See for example column 4, lines 26 to 66, column 11, lines i to 54, and column 2, lines 54 to 68, of Spanier. The use of a pH of 2 to 5, it is disclosed, results in a palatable product. See column3, lines 15 to 21. Citric acid contributes to the flavor of the dog snack--column 8, lines 25 to 27.
U.S. Pat. No. 4,822,626 (Spanier et al.) discloses a coated canine biscuit wherein the coating comprises 10 to 40 percent by weight of dextrin, 10 to 50 percent by weight of meat, 10 to 30 percent by weight of modified corn starch, and i to 5 percent by weight of xanthan based on the total weight of dry solids. The use of an edible organic acid to obtain a coating composition having a pH of less than 6 is not disclosed in Spanier et al.
U.S. Pat. No. 5,015,485 (Scaglione et al.) discloses a coating composition for canine biscuits wherein the coating comprises 2 to 30 percent by weight of maltodextrin, 0.5 to 1.75 percent by weight of lecithin, 0.05 to 2.5 percent by weight of salt, 0.1 to 10 percent by weight of modified corn starch, 0.1 to 3 percent by weight of vegetable fat, 0.1 to 5 percent by weight of animal fat, and 0.05 to 1.5 percent by weight of xanthan gum. However, Scaglione et al. does not disclose the use of potassium sorbate, spray dried poultry byproduct digest, or an edible organic acid, particularly citric acid, to obtain a coating composition having a pH of less than 6. See for example Table 1 at columns 13 and 14 of Scaglione et al.
U.S. Pat. No. 5,000,940 (Staples et al.) discloses coating compositions for dog biscuits and is similar to U.S. Pat. No. 5,015,485. See for example column 14, lines 6 to 24, of Scaglione et al.
U.S. Pat. No. 5,114,704 (Spanier et al.) discloses coating compositions for rawhide (chews for dogs) and is similar in the coating composition disclosure to that of U.S. Pat. No. 5,015,485. See for example Table 1 at column 14 of Spanier et al. The coating solution in Spanier et al. typically had a pH in the range of 5 to 5.8.
Citric acid is used in the dog biscuits marketed by Nabisco, Inc., under the registered trademark "MILK BONE". Dogs like the flavor provided by the citric acid.
Acidulents are used in processed food products as an aid in sterilization. Sterilization of canned food products, in particular, depends on the thermal kill efficiency of the heat applied in retorts and other processing equipment. Many bacteria are highly resistant to heat and in some instances revert to a spore form which can survive high temperatures for a long period of time. Incomplete sterilization can result in instances of botulism or food spoilage. Bacteria and other deleterious microorganisms are more susceptible to thermal kill in a low pH environment. So acidification to lower the pH to a safe level is often used. Many food products, which formerly could not have been adequately sterilized, are now safely processed and maintained for long periods of time through the technique of acidification. Johnson, Arnold H., et al., "Encyclopedia Of Food Technology", The Avis Publishing Company, Inc. (1974), p. 1.